How do Ottawa contractors deal with control joints when applying epoxy flooring

Handling Control Joints During Epoxy Floor Installation in Ottawa

Control joints — the straight lines cut or tooled into your garage floor to manage where concrete cracks — are one of the most important details in any Ottawa epoxy flooring project. Professional contractors have two main approaches: fill and coat over them to create a seamless surface, or honour the joints by maintaining them through the epoxy system. The right choice depends on your floor's condition, the type of epoxy system being installed, and whether the joints are still actively moving with Ottawa's seasonal temperature swings.

The most common approach in Ottawa residential garages is to fill the control joints with a flexible joint filler and then coat the entire floor with epoxy for a seamless look. Contractors use a semi-rigid polyurea or polyurethane joint filler that bonds to both sides of the joint and retains enough flexibility to handle minor seasonal movement. The filler is applied flush with the concrete surface, allowed to cure, and then the epoxy system goes over everything. This method produces the cleanest appearance and is the standard for decorative flake and metallic epoxy systems. The cost for joint filling typically runs $3 to $6 per linear foot, and a typical two-car Ottawa garage has 40 to 80 linear feet of control joints, adding $120 to $480 to the project.

However, filling joints is not always the best strategy. In Ottawa's extreme climate — with temperature swings exceeding 65 degrees Celsius annually — garage slab joints experience significant seasonal movement. Unheated garages see the concrete contract in winter and expand in summer, and those control joints are doing real work absorbing that movement. If the joints are filled with a product that is too rigid, or if the epoxy coating over filled joints cannot flex, you will see cracks telegraph through the epoxy directly along the joint lines. This is called reflective cracking and it is one of the most common epoxy failures in Ottawa garages.

The alternative approach is to honour the joints — the contractor coats the floor with epoxy but cuts back through the cured coating along the original joint lines using a crack chaser or grinder, then fills just the epoxy-lined joints with a colour-matched flexible sealant. This maintains the joints' ability to move while still providing a coated, protected floor surface. This method costs slightly more in labour but provides a more durable result in unheated Ottawa garages where joint movement is significant. It is the preferred method for 100 percent solids epoxy systems, which are rigid and less tolerant of substrate movement.

For polyaspartic and polyurea coatings, which have greater flexibility than traditional epoxy, filling and coating over joints works more reliably because the coating itself can handle minor movement without cracking. This is one of the reasons polyaspartic systems have become increasingly popular in Ottawa — they are better suited to the demands of our climate.

When getting quotes, specifically ask each contractor how they plan to handle your control joints. A professional who does not mention joint treatment at all during the quoting process may not be giving this critical detail the attention it deserves. The Ottawa Construction Network directory at justynrookcontracting.com can help you connect with flooring contractors who understand the specific challenges of Ottawa's climate.

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